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Apple TV lose HDMI signal/endless loop

Blacktip

Blacktip

macrumors member
Original poster
Oct 26, 2021
35
22
Last week, my Apple TV (4K, 1:st gen.), suddenly lost the connection to the TV and refused to show any signal. I tried pulling the power cord and reinserting, but it only showed a blinking white led at the front. Tried to reset with holding down buttons on the remote, tried powering off for more than an hour, tried three different HDMI-cables, verified that the wifi was up and running, tried all 4 different HDMI-ports on the TV. Nope, nothing. Just a blinking white light.

'Ok then', I thought. 'Perhaps end of the life, and lucky me who have another Apple TV (4K, 2:nd gen.) in the kids tv-room. So, I hooked up that other ATV to the TV and everything worked just fine. Well, up until 48 hours later when the Apple TV started to act exactly like the first one. The only difference was that I now saw occasional signals/booting up-traces on the TV, but 2-3 seconds later the TV (A Sony Bravia) showed "No signal". After various key presses on the ATV remote, I got to a screen that asked me if I wanted to perform a factory reset (not the exact wording though), and so I did. Well, tried to. The signal to the ATV seems to be working for a couple of second, and then *poof* – gone. I once got to be able to perform 4-5 steps in the initial flow you do when setting up a new device, but in the middle of the "use iPhone to fix all setting-flow", the signal got lost, and I was back to square (step) one again. Tried to set up the ATV at the former TV it was hooked up to, but same sad result. Even tried to get it to show a steady signal on my LG monitor via HDMI, but no sign of a connected device there.

Now, how plausible is it really that two different Apple TV:s decide to stop working within days from each other? Could it be something else, like a silent firmware being pushed out from Apple that went bad? I really don't think it can be anything else.

I was hoping for a solution to be able to hardwire the machines directly to my Mac (or PC), but since Apple removed the USB-port on the hardware, that's not simply possible, right? In vain I tried to connect the machine via HDMI to my Mac mini:s HDMI-port, but there's no sign of a connected device. And I guess since iTunes is no more, there would be no way to force-update that way either.

Sigh … what to do?
 
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Reset Apple TV

If you’re having problems, you can reset Apple TV to its factory settings, and optionally update to the latest version of tvOS, as well.
support.apple.com

This shows how to do it hardwired to your computer if it's the Apple TV HD but if it's 4K then look like you'll need to contact tech support.

If you're able to check the Chroma settings before it freaks out make sure it's not on 4:4:4 as that can cause no signal issues.
 
Thanks for the replies. I just realised that I was wrong with the models I was referring to. The first ATV that got wonky is a 4K 1:st gen, and my second machine is a 4K 2:nd gen. Guess I will have to call support (and perhaps try to play around with the remote to be able to set another resolution, if that's the culprit that is).
 
With a Mac and Xcode, you can theoretically also see the system log of those appleTV-s, but by now it remains just a theoretical thing, as the aTV and Xcode need to be paired beforehand.
Or perhaps, with the Console app, it will work also without (have not tried myself):
developer.apple.com

Acquiring crash reports and diagnostic logs | Apple Developer Documentation

Gather crash reports and device logs from the App Store, TestFlight, and directly from devices.
developer.apple.com developer.apple.com
 
I think you should explore whether the issue is Sony Bravia TV related. Try both ATVs in your kids room and if they work there, the issue is probably with the Sony TV. Perhaps a setting got changed on the TV, or needs to be changed. Perhaps the HDMI port you are plugging the ATVs into on the Sony TV is messed up. Odds of two ATVs acting up is much less than the odds for one Sony TV to start acting up.

You can also try using another HDMI port on the Sony TV, if you haven't already done so.
 
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w5jck said:
Odds of two ATVs acting up is much less than the odds for one Sony TV to start acting up.
Click to expand...
Yes, that was also my thought as I wrote in my initial long blurb. So, I just made a factory reset on the Sony TV, went through whatever menu items I could find that could give out any hint on HDMI- or image settings (didn't really see anything out of the ordinary). I then tried another initial setup of my 4K 2:nd gen Apple TV. Interestingly enough, the setup started the same way as earlier, with a lot of flickering and (what I think) frequency fixing and image formatting. But lo and behold – I was able to go all the way with the setup and then installed the apps I wanted. We'll see how things are the next days though. But yeah, one Apple TV saved from being tossed in the trash :)

Also: I found this thread that describes flickering and signal loss: https://discussions.apple.com/thread/251355868
The OP states that he/she had to turn off the ability to have the Apple TV switching on/off + controlling any connected devices. I decided to keep my set to on (since it's very convenient). Might change that setting if problem arise again.
 
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Going direct from ATV to your Sony TV? I would also try setting the ATV to 1080 only to see if it's related to cables. Of course like you, that's the first thing that comes to mind.
 
shakopeemn said:
Going direct from ATV to your Sony TV? I would also try setting the ATV to 1080 only to see if it's related to cables. Of course like you, that's the first thing that comes to mind.
Click to expand...
My original issue was that I simply couldn't access the Apple TV's menus at all due to a flickering "looking for signal"/"signal lost"-issue when the Apple TV was booting up.
 
Blacktip said:
My original issue was that I simply couldn't access the Apple TV's menus at all due to a flickering "looking for signal"/"signal lost"-issue when the Apple TV was booting up.
Click to expand...

That sounds familiar. My 2016 OLED doesn't support Dolby Vision 4-4-4 and if my ATV somehow gets changed from 4-4-2, I get that behavior as well. Try unplugging the ATV, connect it to a "non Dolby Vision/HDR" HDMI port on the TV and power up the ATV.

Good luck.
 
I came across this thread while researching the problem I've been having with the ATV 4K. It will occasional flicker while I'm watching a program. The screen will go black for a second or two and no audio then comes back on. The screen will show the time remaining if I'm watching a movie. This happens on both of my 4K TVs. I'd say it's been going on for maybe a month or two. It happened a lot while watching a show on Paramount Plus a few days ago. So I went over to watching the program on the app on my TV (both are Samsung). I took a look at the link that is posted above, both of the TVs can be turned on with the ATV remote. Everything worked fine before so I'm wondering what is causing this? Maybe something with one of the software updates?
 
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